add amd64 asm ver enc16blk1

encode_amd64.s

@@ -0,0 +1,66 @@
+//go:build amd64
+// +build amd64
+
+#include "textflag.h"
+
+// enc16blk1(mask uint16, in, out []byte)
+//    for bit 1 (actual enc128blk1)
+TEXT ·enc16blk1(SB), NOSPLIT, $0-56
+    // create mask
+    MOVQ ·mask+0(FP), BX
+    ANDQ $0xffff, BX
+    BSWAPQ BX
+    MOVQ BX, AX
+    SHRQ $16, AX
+    ORQ  AX, BX
+    SHRQ $16, AX
+    ORQ  AX, BX
+    SHRQ $16, AX
+    ORQ  AX, BX
+    // load source addr
+    MOVQ ·in+8(FP), SI
+    // load source len
+    MOVQ ·inlen+16(FP), CX
+    // load dest addr
+    MOVQ ·out+32(FP), DI
+    // go forward
+    CLD
+lop:
+    LODSB
+    // 8 -> 64
+    XORQ DX, DX
+    SHLB $1, AX
+    SETCS DX
+    SHLQ $16, DX
+    SHLB $1, AX
+    SETCS DX
+    SHLQ $16, DX
+    SHLB $1, AX
+    SETCS DX
+    SHLQ $16, DX
+    SHLB $1, AX
+    SETCS DX
+    // add mask
+    MOVQ AX, R8
+    LEAQ 0(DX)(BX*1), AX
+    BSWAPQ AX
+    STOSQ
+    // 8 -> 64
+    XORQ AX, AX
+    SHLB $1, R8
+    SETCS AX
+    SHLQ $16, AX
+    SHLB $1, R8
+    SETCS AX
+    SHLQ $16, AX
+    SHLB $1, R8
+    SETCS AX
+    SHLQ $16, AX
+    SHLB $1, R8
+    SETCS AX
+    // add mask
+    ADDQ BX, AX
+    BSWAPQ AX
+    STOSQ
+    LOOP lop
+    RET